The series was created by Terence Winter. Winter is an executive producer and the series show runner. He was previously a writer and executive producer on The Sopranos and has won multiple awards for his work on that series. He drew crew members from The Sopranos to work on Boardwalk Empire.

In developing the series Winter worked closely with fellow executive producer and pilot director Martin Scorsese. Winter stated that Scorsese weighs in on the casting decisions, watches all the cuts and dailies. Up until the shooting of the show's first season, Scorsese and Winter would meet every Sunday afternoon to review what went on during the week and where Scorsese would have comments and suggestions.

Scorsese and Winter are joined as executive producers by Mark Wahlberg, Stephen Levinson and Tim Van Patten. Van Patten had been a regular director on The Sopranos and also served as a regular director for Boardwalk Empire. Lawrence Konner was a co-executive producer. Konner also wrote for the show and had previously been a writer on The Sopranos. Howard Korder and Margaret Nagle served as supervising producers and writers for the first season. The crew were recognised with multiple Emmy Award nominations for their work on the first season.

Scorsese directed the pilot, establishing a template for the series aesthetic. Other directors later emulated the pilot to make the show appear seamless. Scorsese's fellow executive producer Tim Van Patten was the seasons most frequent director.

On the eve of Prohibition, Atlantic County TreasurerNucky Thompson condemns alcohol at a Women's Temperance League meeting, where he is seen by Margaret Schroeder, a pregnant housewife who later comes to him for help in getting her alcoholic husband Hans a job. But Nucky is duplicious and that same night he privately shares with his ward bosses, his brother SheriffEli Thompson and the Mayor of Atlantic City a plan to make huge profits selling bootlegged liquor. At a Countdown to Prohibition party at Babette's Supper Club, Nucky assures Jimmy Darmody, a recently returned WWI vet and former protegé of his, that his appointment as "Man Friday" to the new Chief Clerk of the Fourth Ward, Paddy Ryan, will lead to bigger and better things. Jimmy, however, has higher aspirations - as well as a lack of patience - and ends up making a deal behind Nucky's back that could have dire consequences for the both of them.

Nucky is paid a visit by straight-arrow Agent Nelson Van Alden, who feels that Nucky has pinned the recent shootings on a scapegoat (Hans Schroeder). Nucky utilizes his brother Elias' position as sheriff, to visit Hans' widow Margaret Schroeder in the hospital and help do some damage control. Nucky receives a visit from Margaret before heading out for a night on the town, as she has come to return the hush money Elias had given her. She asks for his help providing for her young children, but through an honest job. After an incident involving Al Capone's beating of a reporter in Chicago, Nucky contemplates the upcoming election with his aging mentor, Commodore Louis Kaestner...

Jimmy Darmody now works for Al Capone's Chicago boss, Johnny Torrio, and lives in a brothel Torrio runs. Capone and Darmody attempt to strongarm a bar owner manager to buy his liquor from Torrio; when he is uncooperative, Capone beats him. They meet with Torrio's rival, Sheridan, and compromise on business arrangements. Torrio is more impressed by Darmody's negotiation than by Capone's brutality. One of Sheridan's men retaliates, attacking and disfiguring Jimmy's current girlfriend Pearl, a prostitute in Torrio's brothel.

In Atlantic City, as Nucky plans his "surprise" birthday party, he worries about the political impact of the murder of Chalky White's driver. Eli delivers the leader of the local chapter of the Ku Klux Klan to White, who tortures him until he is satisfied that the Klan was not involved in the killing. At Nucky's party, Senator Edge tells Nucky he will not receive expected roadbuilding funds needed to complete Atlantic City's development, which will go instead to Frank Hague...

Margaret wakes to see ward boss James Neary's men offloading beer barrels into a garage behind her house. She meets Nucky on her way to work, but he disappoints her with his sudden aloofness. After discussing the garage at a Temperance League meeting, Margaret and a colleague manage to meet with Nucky, who promises to take action but does nothing. Margaret sees the deliveries again that night; brushed off by Neary and ignored altogether by Thompson, she reports Neary's garage to Van Alden. The agent initially dismisses the operation as one of hundreds in the city, but she catches his interest by mentioning that Neary works for Nucky Thompson...

AldermanGeorge O'Neill makes his collection rounds along the boardwalk. He visits a Chinese restaurant near to the Cafe Beaux-Arts, counts the money into a leather pouch and then crosses it off his list. He is approached by Pius D'Alessio who insults him, spits in his face and then runs off. O’Neill gives chase and as he rounds a corner Ignacious D'Alessio steps out and hits him in the head knocking him out. Ignacious steals the pouch full of money and leaves O’Neill to wake up to seagulls circling above him.

Nucky Thompson and Lucy Danziger share a poscoital embrace at the Ritz Carlton Hotel. He is dozing as she asks him what makes him feel good and worries about his faithfulness. She describes herself as a little tiger cub and rakes her nails down his chest, drawing blood. The pain brings Nucky to annoyed wakefulness. He tells her to calm down, puts on a robe and goes to the bathroom. She smokes a cigarette, alone...

Nucky and Eli's father is becoming increasingly frail and losing his independence. Returning to his childhood home causes Nucky to ruminate on his violent, unhappy upbringing. Jimmy attends a veteran's hospital due to increasing pain from his battlefield injury. He meets Richard Harrow, a veteran sniper with a horrific facial injury. Jimmy recruits Richard in a plan to kill the gangster who cut Pearl's face. Lucky Luciano starts a collaboration with the D'Alessio brothers to harm Nucky. Nucky burns his father's house down to finish with the past.

Nucky visits Chicago for the Republican National Convention, where he finds himself intrigued by the candidacy of Warren G. Harding over more established candidates, despite the fact that he meets Warren's mistress and bastard child. He promises Harding's manager the votes of the New Jersey delegation in exchange for blocking Senator Edge's nomination for the vice-presidency, knowing that his former ally has secretly sided against him in funding new roads for Jersey City rather than Nucky's own Atlantic City.

Nucky stops by Johnny Torrio's brothel looking for more information on Harding. As Nucky talks to Torrio and a local judge, Jimmy comes downstairs and runs into his old patron. Nucky behaves coldly towards Jimmy, criticizing him for never writing his family. It is revealed in the episode that Internal Revenue agent Van Alden, still working out of Atlantic City's post office to investigate Jimmy, has been intercepting the steady stream of money and letters Jimmy sends to his wife...

A wounded Eli identifies the D'Alessio brothers as the men who robbed the casino and shot him. On the boardwalk, Margaret talks to Warren Harding's mistress, Nan Britton, whom Nucky has brought along from Chicago. Nan explains how she and Warren met and how, in order for him to win the presidential election, he cannot support her and their child.

Margaret and Nan go to Madame Jeunet's to buy a dress for Nan. Madame Jeunet asks Margaret to persuade Nucky to reduce the exorbitant rent he charges. At first, Margaret broaches the issue directly, but this only angers Nucky. Taking a different tack, she then tells Nucky she is worried about not looking good for him if Madame Jeunet leaves. This works, and when Madame Jeunet gratefully offers Margaret a dress for her daughter, Margaret instead uses her newly found influence to get a more expensive dress for herself...

Continuing the plotline from the last episode, Richard Harrow is now staying at the Schroeder house, although his face injury is scaring the children. Agent Sebso is sent home to rest over the protests of Van Alden, for killing Billy Winslow supposedly in self-defense. Jimmy has taken up residence with his family and attempts to reconnect with Angela. Rothstein chides the D'Alessio brothers and Mickey for not doing enough research on Nucky's butler, Eddie, and for shooting a civilian during the failed assassination attempt.

Agent Van Alden continues to probe deeper into the killing of Billy Winslow, prompting Agent Sebso to make a call to Nucky asking for some leads to regain his boss's trust. Looking for a still, the two encounter a black church's river baptism. When Sebso, who is Jewish, puts in for a transfer to Michigan, Van Alden brings him to the river to be baptized. However, Van Alden holds Sebso under the water too long, drowning him. Whether Van Alden planned the murder is left unclear...

Agent Van Alden has requested a transfer out of Atlantic City, although his supervisor asks him to reconsider. The Commodore's maid admits she tried to poison him because of his mistreatment. Nucky lets her leave Atlantic City quietly over the protests of the Commodore. Nucky is increasingly stressed about the election, which the Democrats stand a good chance of winning. Chalky White offers to deliver the black vote for $10,000, a new car, and an invitiation to the (whites only) Election Night victory party...